Water must be liberal while Arum Lilies are out of doors, unless the weather is rainy, and while in pots they need less water from autumn to spring (counting March as springtime), then plenty until May, for it is usually at the end of the last month that they are first stood out, then planted out, or immediately 'plunged.' The winter temperature for this African Richardia can be quite low: even 40o will suffice, or fifteen more degrees can be borne ; in the months from March to May 50o to 60° will be correct. Some compound fertiliser solution, or half an ounce of Peruvian guano in a gallon of water, will stimulate the plants satisfactorily from the beginning of florescence to its cessation.
Richardia Hastata is my choice of a yellow variety.
At most Spring Flower Shows of late years exhibits of Cape Cowslips, or Lachenalias, have made visitors eager to grow some. The bulbs cost from five to ten shillings a dozen, not allowing, of course, for any fancy prices of new introductions, should be obtained in August, and put in at once, three in a five-inch pot, or more if pretty groups are more desired than the finest flowers.
Opinions differ as to the right depth. I could quote noted authorities who say only 1/2 inch deep, and others who advise 2 1/2 to 3 inches. Personally, I vote for 2 inches, and top-dressing can be given later. Use a compost of loam, leaf-mould, very old cow-manure, and coarse river-bed or roadside sand. Drainage arrangements must be adequate, and the addition of a little powdered charcoal to the soil is a safeguard. Place the bulbs on a sprinkling of sand. Put the pots into an airy greenhouse or cold frame, not exposed to full sunshine, yet close to glass, until November, giving scarcely any water. Then place them in a sunny position in a greenhouse with a certain temperature of 45o, or as much as 55o. From the time the foliage is made, to the end of the flowering, Lachenalias want a good deal of water, and as the buds begin I like to apply a thin mulch of old cow-manure sprinkled with fertilizer, which feeds them excellently.
If liquid manures are given, instead of a mulch, these must be discontinued as soon as the buds are opening.
When blossoming ends the plants should be exposed to sunshine, either out of doors stood on cinders or in cold frames. Water is gradually withheld, and the bulbs then ripen. Lachenalias are as charming as Achimenes for filling hanging baskets or wall-pockets. The flowers are yellow, yellow-green-and-red, and crimson-and-green.
The tuberous Trop‘olums are most meritorious, and here we meet with climbing plants that count among bulbous ones, fit for wreathing pillars or covering trellis-work, or netting against walls, or making canopies across the inner roof of greenhouses.
The familiar type is Trop‘olum tuberosum, which has red-and-gold blossom, and will survive out of doors, in dry sunny situations, if tubers are lifted like those of Dahlias. It is a good tub plant, undisturbed, in a moderately warmed greenhouse, unless there is too much damp; or may be lifted annually, then replanted. It thrives in poor soil.
Trop‘Olum Azureum, blue, only grows to a height of 3 feet, Trop‘olum tricolorum to as much as 10 feet, being a colour blend of red, gold and black. Give these greenhouse species a compost of peat, leaf-mould, loam, and silver sand in equal mixture. Start a tuber in a four-inch pot, 1 inch below the compost surface, in August or October; stand the pot in a glasshouse of from 45o to 55o, and see that the contents do not dry, but water very little until the growth is well up. Then repot tenderly into a six-inch pot. Train the delicate branches to strings, sticks, or painted wire, and give liquid manures now and then when buds show. After flowering is finished the foliage turns yellow, and then no more water should be given. Pull down the dried dead branches, and put the pots in a cool shelter of some sort. The greenhouse temperature for blooming them is from 550 to 650, but that is too hot for the plants afterwards, during the short period before they are restarted. This is done by repotting them in the same-sized pots, but new compost.
For making a greenhouse gay the Indian Shot Plant, or Canna, is of great value. The tubers can be bought, in fine mixture, in March, potted singly in six-inch pots of ordinary rich compost, and started in moderate heat. When growing freely they can be well watered, and can endure a really high temperature, in spite of the fact that they can be bloomed out of doors, or in sunny room windows, by gardeners who have no hot-houses. After the gorgeous vermilion, yellow, salmon, blotched, spotted, striped blossoms are over water must be gradually withheld, as the roots need a time for rest. Cannas increase rapidly, so soon require dividing. For their culture from seed see Chapter XVIII (Agapanthuses, Camassias, Cannas, Etc).
Pots of Lilies of the Valley are a source of such pleasure that space must be spared for the subject.
It is best to buy 'crowns,' which are single roots. Twelve or fifteen may go into a six-inch pot, which should contain equal portions of good fresh loam and leaf-mould. Potting may begin in October.
Cover each pot by inverting another six-inch one above it, and stand them in a cold frame, airy shed, room, or unheated greenhouse, until January, taking care meanwhile that the compost never dries up. From then onwards either keep them in the ordinary conservatory, or, after ten days or so in an intermediate temperature, introduce them to a high one. Pots of Lilies of the Valley brought into a forcing-house in November, after being potted as above, will soon bloom.
Now that 'retarded' crowns are obtainable, the Lily of the Valley can be had in blossom nearly all the year, from pottings in autumn, winter and spring. The recipes for using these and the other bulbs are astoundingly varied.
Pots may be plunged in coco-nut-fibre that is kept damp, instead of having inverted pots over them. Or they will succeed in bowls of moss-fibre and sea-shell, and if put into a box thus in a hot-bed, or above a hot cistern, can be forced into flower in less than a month. In fact, pottings may be undertaken at intervals from September to April; then, so long as the roots never lack moisture, and the green growth is gently sprayed, or can feel a moist atmosphere, the batches can be flowered leisurely, or hurried by stove heat.
The 'crowns' are usually barely covered by compost. They can be grown touching each other for rapid forcing, or two or three inches apart, and are often cultivated in boxes, for cutting. Forced bulbs should be thrown away.
There is now a pale pink variety of the Lily of the Valley.